What do the Aka Pygmies, Polish Highlanders and French composer Claude Debussy have in common with Eric Johnson, Bumblefoot and Paul Gilbert? They all tapped into the power of the pentatonic scale to ignite their music and pull listeners to their feet. The pentatonic scale crosses all genres and is embraced by all cultures -- five notes; infinite musical possibilities. And if you play any style of rock then the pentatonic scale is your #1...